The invention relates to a orthotropic steel plate deck bridge consisting of a combination of steel plate deck, closed ribs and open ribs connected together by welding. The new structural member has a large torsion and flexural rigidity, with a good response to the applied loads and an increased fatigue life expectancy.
Known orthotropic steel plate deck systems have as their objective the use of a steel plate working in two perpendicular directions, reducing the amount of steel required to transfer the applied loads, hence the dead load of the bridge. The steel plate is stiffened by ribs and works as a top flange in the rib's longitudinal direction, and is acting as top flange for the steel girders in the perpendicular direction.
According to the first alternative method, the steel plate deck is welded to an open rib system. The ribs are made of steel and varies in shapes from a simple plate to an invert T form. The structural steel member made-up of steel plate and open ribs has no torsional rigidity and a relatively small flexural rigidity, limiting the spacing between ribs to around 10 inches, and the spacing between transverse steel girders which support the ribs to around 7 feet. The whole system is composed of large numbers of ribs and steel girders, exhibiting poor response to the applied loads and relatively reduced fatigue life expectancy.
According to the second alternative method, the steel plate deck is welded to a closed rib system. The ribs are made of steel and varies in shapes from a rectangular to circular form. The structural steel member made-up of steel plate and closed ribs has relatively large torsional rigidity and a small flexural rigidity, limiting the spacing between transverse steel girders which support the ribs to around 15 feet. The spacing between ribs is limited by the thickness of the steel plate and is around 15 inches. The whole system is composed of large number of ribs, having an inadequate fatigue life expectancy.
To overcome the shortcomings of the existing methods, the present invention is developed to produce an orthotropic steel plate deck bridge with large torsional and flexural rigidity, with improved response to the applied loads and with an prolonged fatigue life expectancy of the deck. The double rib system also uses a reduced quantity of steel per square foot of bridge deck, is easier to fabricate and its adequate for field splicing.